ENCLOSED FOUNDATION

PURPOSE:To construct a stable and earthquake-proof foundation by a method in which an underground enclosed wall is constructed around the ground beneath a structure and all or a part of the underground enclosed wall is formed of a water-permeable material. CONSTITUTION:A trench is excavated around the ground 5' beneath a structure 4 (e.g., petroleum tank, etc.) built on soft ground 5, and concrete slabs (or panels) having a water permeability are wholly or partly erected in the trench in order to construct an enclosed foundation 6 consisting of the underground enclosed wall. The load of the tank 4 acts on the ground 5 below the foundation 6 integrally with the ground 5', being beared on a slippery resistance R, a pressing force P, and a frictional force N. When the foundation 6 is formed of a water- permeable material, water in the underground 5' is absorbed by the foundation 6 as soon as earthquake occurs and drained and dissipated from the upper end 6a, so that the liquefaction of the ground can be prevented.